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77 lines
2.4 KiB
77 lines
2.4 KiB
## Add a FeatureOption.enable_if and .disable_if |
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These are useful when features need to be constrained to pass to [[dependency]], |
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as the behavior of an `auto` and `disabled` or `enabled` feature is markedly |
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different. consider the following case: |
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```meson |
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opt = get_option('feature').disable_auto_if(not foo) |
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if opt.enabled() and not foo |
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error('Cannot enable feat when foo is not also enabled') |
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endif |
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dep = dependency('foo', required : opt) |
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``` |
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This could be simplified to |
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```meson |
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opt = get_option('feature').disable_if(not foo, error_message : 'Cannot enable feature when foo is not also enabled') |
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dep = dependency('foo', required : opt) |
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``` |
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For a real life example, here is some code in mesa: |
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```meson |
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_llvm = get_option('llvm') |
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dep_llvm = null_dep |
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with_llvm = false |
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if _llvm.allowed() |
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dep_llvm = dependency( |
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'llvm', |
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version : _llvm_version, |
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modules : llvm_modules, |
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optional_modules : llvm_optional_modules, |
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required : ( |
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with_amd_vk or with_gallium_radeonsi or with_gallium_opencl or with_clc |
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or _llvm.enabled() |
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), |
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static : not _shared_llvm, |
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fallback : ['llvm', 'dep_llvm'], |
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include_type : 'system', |
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) |
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with_llvm = dep_llvm.found() |
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endif |
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if with_llvm |
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... |
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elif with_amd_vk and with_aco_tests |
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error('ACO tests require LLVM, but LLVM is disabled.') |
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elif with_gallium_radeonsi or with_swrast_vk |
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error('The following drivers require LLVM: RadeonSI, SWR, Lavapipe. One of these is enabled, but LLVM is disabled.') |
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elif with_gallium_opencl |
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error('The OpenCL "Clover" state tracker requires LLVM, but LLVM is disabled.') |
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elif with_clc |
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error('The CLC compiler requires LLVM, but LLVM is disabled.') |
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else |
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draw_with_llvm = false |
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endif |
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``` |
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simplified to: |
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```meson |
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_llvm = get_option('llvm') \ |
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.enable_if(with_amd_vk and with_aco_tests, error_message : 'ACO tests requires LLVM') \ |
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.enable_if(with_gallium_radeonsi, error_message : 'RadeonSI requires LLVM') \ |
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.enable_if(with_swrast_vk, error_message : 'Vulkan SWRAST requires LLVM') \ |
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.enable_if(with_gallium_opencl, error_message : 'The OpenCL Clover state trackers requires LLVM') \ |
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.enable_if(with_clc, error_message : 'CLC library requires LLVM') |
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dep_llvm = dependency( |
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'llvm', |
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version : _llvm_version, |
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modules : llvm_modules, |
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optional_modules : llvm_optional_modules, |
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required : _llvm, |
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static : not _shared_llvm, |
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fallback : ['llvm', 'dep_llvm'], |
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include_type : 'system', |
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) |
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with_llvm = dep_llvm.found() |
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```
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